This document defines and classifies different types of nystagmus. It describes the key characteristics of different nystagmus including congenital motor nystagmus, periodic alternating nystagmus, spasmus nutans, vestibular nystagmus, upbeat nystagmus, downbeat nystagmus, and nystagmus associated with strabismus. It also discusses the mechanisms, localization, and treatment options for nystagmus including optical devices, pharmacology, botulinum toxin injections, and surgery.

2. Nystagmus
Maj Md Ferdous Islam
FCPS Part 2 Trainee
Dept of Ophthalmology
CMH,Dhaka

3. Defination
Nystagmus is an involuntary, rhythmic to and
fro
oscillation of the eyes
2 phases
1. slow drift from the target of interest
2. corrective saccade back to the target

4. Terminologies
 Amplitude
 Frequency
 Direction
 Null zone
 Pursuit / Saccade
 Conjugate / Dissociated
 Jerk / Pendular

5. Amplitude is the angular distance
traveled during nystagmus (excursion of
the nystagmus)
 Low : less than 5 Degree
 Moderate: 5-15 Degree
 High: > 15 Degree
Direction The fast component defines
the direction of Nystagmus

6. Frequency is the number of to and fro
movements in one second
 Slow : (1-2 Hz)
 Medium : (3-4 Hz)
 Fast: (5 Hz or more)
Null zone
 Gaze location where nystagmus is
minimal.
 Located in the gaze opposite the fast
component

7. Pursuit /Saccade
 Pursuit eye movements allow the eyes
to closely follow a moving object
 Saccades are quick, simultaneous
movements of both eyes in the same
direction

8. Conjugate/Dissociated
Conjugate :
nystagmus which is symmetric in
direction, amplitude and rate
Dissociated:
when it differs in any one of the
parameters between two eyes

9. Jerk / Pendular
Jerk nystagmus Pendular nystagmus
Alternation of slow phase drift
rapid corrective saccade in
opposite direction
Sinusoidal oscillation with slow
phase
in both directions and no corrective
saccade
Direction of jerk nystagmus =
direction of the fast phase
Pendular nystagmus may be
horizontal
or vertical
Right or left beating nystagmus
Upbeat or downbeat nystagmus
Not characterised by right, left, up,
down beating as there is no fast
phase

11. Alexanders law
It states that the amplitude of jerk
nystagmus is largest in the gaze of
direction of fast component

12. Mechanism of nystagmus
Foveal centration of an object of regard
is necessary to obtain the highest
level of visual acuity
 Three mechanisms are involved in
maintaining foveal centration of an
object of interest:
Fixation
The vestibulo-ocular reflex
The neural integrator

13. Fixation
 Fixation in the primary position
involves the visual system's ability to
detect drift of a foveating image and
signal an appropriate corrective eye
movement to refoveate the image of
regard.
 Involved with the oculomotor system

14. Vestibulo-ocular reflex
 The vestibulo-ocular reflex is a
complex system of neural
interconnections that maintains
foveation of an object during changes
in head position
 The proprioceptors of the vestibular
system are the semicircular canals of
the inner ear.
 The semicircular canals respond to
changes in angular acceleration due
to head rotation

15. Neural integrator
When the eye is turned in an extreme
position in the orbit, the fascia and
ligaments that suspend the eye exert an
elastic force to return toward the primary
position
To overcome this force, a tonic contraction
of the extraocular muscles is required.
A gaze-holding network called the neural
integrator generates the signal. The
cerebellum, ascending vestibular
pathways, and oculomotor nuclei are
important components of the neural

16. Classification
Based on Aetiology
Based on Onset
Based on direction of Movement
Based on Pattern of movement
Based on Pattern of Manifestation
Based on Amplitude
Based on Frequency

17. Congenital nystagmus
Usually not noted at birth but becomes
apparent during first few months of life
1. Congenital Motor Nystagmus
2. Congenital Sensory Nystagmus
3. Periodic alternate Nystagmus
4. Latent Nystagmus( fusion
maldevelopment nystagmus
Syndrome)
5. Manifest latent Nystagmus

18. Congenital Motor Nystagmus
 Horizontal
 Uniplanar
 Bilateral
 Conjugate
 Head turn to achieve Null Point
 Improves with convergence
 Worsen on attempted fixation
 Reverse response to OKN stimulus (
fast phase in direction of moving OKN
drum)

19. Periodic alternating nystagmus
(PAN)
 PAN is a conjugate, horizontal jerk
nystagmus with the fast phase beating in
one direction for a period of
approximately 1-2 minutes.
 The nystagmus has an intervening
neutral phase lasting 10-20 seconds
 The nystagmus begins to beat in the
opposite direction for 1-2 minutes then,
the process repeats itself

20.  Periodic alternating head turn to
minimise nystagmus & oscillopsia
 Causes: lesions of the cerebellum

22. Spasmus nutans
Triad of symptoms:
1. Nystagmus
2. Head nodding
3. Torticollis (head tilt or head turn)
Onset usually in the first year of life (3-
15 months).
Disappears by 3-4 yrs of age

23.  The nystagmus typically consists of
small-amplitude, high frequency
oscillations and usually is bilateral, but
it can be monocular, asymmetric, and
variable in different positions of gaze
 Usually benign
 Neuroimaging recommended (
gliomas may mimic spasmus nutans)

24. Acquired
Physiological:
 End point nystagmus
 Vestibular (caloric or rotational)
nystagmus
 Optokinetic nystagmus

25. End point nystagmus
 Jerk nystagmus
 On looking extreme lateral or upwards
 Angle of gaze > 45 Degree

27. Vestibular nystagmus
 Jerk nystagmus
 Altered inputs from vestibular nuclei to
horizontal Gaze Centre(PPRF)
 Demonstrated by caloric test: normal
response
 Cold water : opposite side
 Warm water : same side
 Cold water in both ears: upwards
 Warm water in both ears : downwards
COWS
Cold slows things down

28. Optokinetic nystagmus
 Jerk nystagmus
 Induced by moving a full visual field
stimulus
 Slow phase (pursuit) : eye follows the
target
 Fast phase ( saccade): eye fixates on
next target
Uses: Detecting malingering
Testing visual potential in children

30. Pathological
 Nystagmus associated with poor vision
(sensory)
 Anterior segment: cataract, aniridia
 Retinal diseases: RB, ROP, Intrauterine
infections
 Nystagmus associated with neurological
diseases (motor)
1.End gaze paretic nystagmus ( horizontal
gaze center)
2.Convergence retraction nystagmus(
vertical gaze, parinaud’s)

31. 3.Vestibular nystagmus:
Central ( brainstem nuclei)
Peripheral ( labyrinths, VIII CN)
4.Downbeat nystagmus(
cervicomedullary junction)
5.Upbeat nystagmus( cerebellum,
medulla)
6. Seesaw nystagmus (parasellar
lesions)
7. Periodic Alternating Nystagmus

32. Gaze paretic nystagmus
 Most common type
 Absent in primary position and is not
visually disabling
 Beats in the direction of gaze
 Causes: Anticonvulsants
Brainstem lesions
Cerebellar lesions

34. Convergence-retraction
nystagmus
 Not truly a nystagmus
 Bil adducting saccades causing
convergence of both eyes
 Elicited by having the patient to look up,
at which time the eyes converge &
retract
 Causes: Dorsal midbrain lesions

37. Vestibular nystagmus
Feature Peripheral Central
Disease of vestibular
origin
Disease of the
brainstem
Direction Intensity increases
when
the eyes are turned in
direction of fast phase
Direction of nystagmus
may change with gaze
Visual fixation Inhibits nystagmus No inhibition
Severity of vertigo Severe Mild
Induced by head
movements
Often Rare
Associated eye
movement
deficit
None Pursuit or saccadic
defect
Other findings Hearing loss CNS involvement

38. Upbeat nystagmus
 Type of jerk nystagmus with fast
phase upward in primary position
 Often worsens in upgaze
 Causes: lesions of medulla, cerebellar
vermis, midbrain
 Rx: base up prisms in reading glasses
can be used to force the eyes
downward

41. Downbeat nystagmus
 Type of jerk nystagmus with fast phase
downward in primary position
 Often worsens in downgaze
 Oscillopsia is usually prominent
 Causes: lesions at cervicomedullary
junction
 Rx: base down prisms in reading glasses
can be used to force the eyes upward

44. Seesaw nystagmus
 Defined as pendular nystagmus with
elevation and intorsion of one eye
simultaneous with depression and extorsion
of other eye
 Followed by reversal of cycle, so that the
eyes move like a seesaw
 Causes: parasellar lesions, pituitary tumors
 Produces very disabling oscillopsia that
responds poorly to any Rx

46. Nystagmus associated with
strabismus
 Latent /manifest-latent nystagmus
 Manifest nystagmus
 Nystagmus blockage syndrome

47. Manifest nystagmus Manifest-latent nystagmus
Pendular nystagmus Jerk nystagmus
No change on abduction Increased on abduction
No change on covering one eye Increase on covering one eye
Null zone is present Fast phase always towards fixing
eye
Less commonly associated with
infantile esotropia
Always associated with esotropia
Binocular visual acuity same as
uniocular
Binocular visual acuity better than
uniocular

48. Nystagmus blockage
syndrome
 Inverse relationship with esotropia
 Esotropia is a mechanism of blocking
the nystagmus
 The fixing eye is preferred to be in
adduction ,face turn is in the direction
of fixing eye

49. Type of Nystagmus Localizing value
Seesaw Nystagmus Parasellar Tumours, Syringobulbia,
Brainstem Stroke
Downbeat Nystagmus Leison in the foramen Magnum,
Syringobulbia, Lithium and Phenytoin
toxicity , Wernicke Encephalopathy,
Demyelination,Hydrocephalus
Upbeat Nystagmus Posterior Fossa Leisson, drugs,
Convergence Retraction Nystagmus Dorsal Midbrain Syndrome
Bruns Nystagmus Cerebellopontine Angle tumours

50. Nystagmoid conditions
Movements which are not regular and
rhythmic:
 Oculopalatal myoclonus
 Opsoclonus
 Ocular bobbing

51. Oculopalatal myoclonus
 Type of vertical pendular nystagmus
 Coexisting with tremor of the facial
muscles, larynx, palate
 Present during sleep
 Cause : usually develops months after
an infarction or hge involving mollaret
triangle
 Rx: Gabapentine

53. Ocular bobbing
Characterised by conjugate eye
movements,
 beginning with a fast downward
movement
 f/b slow drift back to midline
 Causes: 1. comatose patients with
massive pontine lesion
2.metabolic encephalopathy

54. Superior oblique myokymia
 Defined as oscillation of one eye due
to intermittent firing of the superior
oblique muscle
 Produces oscillopsia or intermittent
diplopia elicited by having the patient
look in the direction of the superior
oblique muscle
 Characterised by monocular, rapid,
intorsional movements

55.  Usually benign
 No underlying etiology is found
 Neuroimaging : r/o post fossa tumors
 Refractory cases: surgical weakning of
the superior oblique muscle can be
performed

57. Treatment
 Nonsurgical : non neurological causes
 1.Optical devices
Glasses: overminus lenses stimulate
accommodative convergence and thus
dampens nystagmus
Contact lenses: helpful in high refractive
errors by giving good visual stimulus
for fusional control

58. Prisms : can be used for 2 purposes
1. To induce fusional convergence by
using 7 PD base out prism in front of
each eye
2. pre op evaluation in a patient with
face turn
 prisms are inserted with the apex in
direction of gaze
 Useful as a diagnostic trial ,but as a
therapeutic alternative are not helpful

59.  Occlusion therapy:
 Trials with conventional occlusion
have been found to be effective
 As amblyopia gets corrected and
vision improves, nystagmus finally
decreases

60. Pharmacologic Mx
These drugs hypothetically inhibit
excitatory neurotransmitters within
CNS
 Baclofen : congenital nystagmus,
seesaw
nystagmus, periodic alternating
nystagmus
 Carbamazepine: widely used for
superior oblique myokymia

61. Pharmacologic denervation
 Botulinum toxin A act by blocking the
neuromuscular transmission
 used in 2 distinct ways to dampen
nystagmus
 3 units of toxin is injected in each of
the 4 horizontal rectus muscles
 Single large dose of drug into the
retrobulbar space
 Effect last for only few months

62. Surgical
 Based on 3 principles:
 To shift the null position if any to the
primary position
 To induce extra convergence
innervation by weakening medial recti,
to dampen nystagmus
 To reduce the amplitude of the
nystagmus by weakening the muscle
force of all recti

63. Thank
You